1. Field of the Invention
The present invention relates generally to supercharging of vehicle engines and more particularly to supercharging vehicle engines using the cooling fan to provide ambient temperature air for the supercharging effect.
2. Description of the Prior Art
The performance of an internal combustion engine is largely a function of the volumetric efficiency of the engine. Incoming fuel charges to such engines are, in normally aspirated engines, inducted by a pressure differential between the ambient atmospheric pressure and the pressure within the engine. By increasing the external pressure through supercharging, volumetric efficiencies can be substantially improved.
While expensive routes and centrifugal superchargers driven by belts or exhaust gases are well known, there are only two types of relatively inexpensive supercharges. These utilize either the engine cooling fan for pressure boost or, alternatively, the ram effect of the vehicle motion to provide a supercharging effect.
Examples of prior art devices using the cooling fan of an engine to provide a supercharger effect may be found in U.S. letters Patent Nos. 2,114,783, 2,175,106 and 2,254,927. In each of these prior art examples, the air for supercharging is collected after it passes the cooling fan and, accordingly, after it is drawn through the radiator. As a result, such air is heated above ambient temperature and is at a density less than that of the ambient atmosphere. As is well known, heated air, being of a diminished density, detracts from the volumetric efficiency of an engine. Thus, while the prior art examples using the cooling fan to provide air at elevated temperatures may provide a net increase in horse power, the potential increase is not realized as a result of the use of air heated by the cooling radiator of the engine.
Air at ambient temperature is provided by the ram effect type of superchargers such as that described in U.S. letters Patent No. 2,852,012. However, while air at ambient temperature is provided by this arrangement, the pressure increase is moderate and entirely a function of the vehicle speed. Accordingly, at lower speeds and in lower ratio gears, the ram effect is greatly diminished. This is to be contrasted to the increased supercharger effect in the higher power ranges of most internal combustion engines when in lower gears and utilizing the cooling fan for pressure increase.
Summarily, the prior art low-cost supercharging mechanisms either utilize heated air for the supercharging effect, or, alternatively, are entirely dependent upon the vehicle speed and of marginal effectiveness in the lower gear ratios even though the engine may be operating at high rpm's and within the optimum power range.